Excursion Soultz-sous-Forêts

Please read the report of the Geothermal field trip to Soultz-sous-Forêts (2015)

In November there was a two days geothermal excursion to Soultz-sous-Forêts, Alsace, organized by our geothermal professor David Bruhn and DAP. The last DAP seminar had this area as a topic as an introduction. With two minivans we drove with a very mixed group, BSc, MSc and PhD students and alumni, to France. This time the excursion’s focus was on the surface facilities, but some outcrops were visited as well.

The excursion started early so we could arrive in Soultz-sous-Forêts just after lunch for a presentation of the EGS (Enhanced Geothermal System). The heat is extracted from the granite in the Rhine Valley at roughly 5 km depth with 4 wells. A fracture zone is created between the wells by hydraulic fracking to circulate water and extract the heat. At the surface there is a pilot plant, used for generating electricity, for research on geothermal energy production and to minimize the environmental and social impact. The results show that a minimal footprint needs to be used and that the fracking has no impact on the community, but providing solid information for people who live nearby is crucial. After the presentation a former production site and a new one were visited.

After these sites it was time to go to the hotel and have diner. We had their specialty, Chourcroute d’alsace. I can recommend everyone to eat this dish, when visiting the Alsace. Another thing this area is famous about is their history in oil, which is all explained in the oil museum nearby our hotel. With pride the owners told us their golden times and how the Schlumberger brothers started their carries there.

The second day started with a visit to the geothermal power plant in Bruchsal, which has research as the main target. Solutions are found for CO2 production the effect of scaling and damage on pumps, pipelines etc. Therefor the power plant is not that profitable in terms of money, but a lot of lessons are learned for future projects. One of the projects is the power plant in Insheim at which we got a tour after Bruchsal.

This powerplant in Insheim is operated by Pfalzwerke geofuture, which is producing water at a temperature of 165 °C from 3.600 m depth . With a production rate of 50-80 l/s, they generate 4.8 MW electric energy.

At the end of the day, we had little time to visit an outcrop of the reservoir used for the production of geothermal energy. Actually it was a still operating basalt quarry, but nevertheless we were allowed to have a nice look!

This successful geothermal excursion is far from the last interesting geothermal activity planned by David Bruhn and DAP. The next seminar will be in February and a geological excursion to Iceland is in the planning as an elective course for MSc/PhD-students. Hopefully we see you there!

Cheers,

Twan Goense and Rogier Crooijmans

Figure 1 – outcrop of the reservoir rock. At the top the Bundsandstein, and below the granite reservoir rock including basaltic dikes.